Guidelines have been promulgated by government and/or industry organizations regulating the maximum energy consumption levels of appliances such as dish washers, clothes washers, dryers, and the like. According to these guidelines, the average energy usage over a predetermined number of cycles of operation of such appliances should not exceed a defined acceptable maximum energy consumption level.
The U.S. Department of Energy, for example, has established an energy factor (EF) which is computed in order to determine energy usage of an appliance. The calculation of the energy factor is based on several inputs, including the temperatures available for selection by a user, estimated probabilities that these temperatures will be selected, the volume of the appliance container into which the articles to be washed and/or dried are placed, fill level in the container, motor energy, and the like.
For example, the energy factor EF for a clothes washer is calculated by multiplying the following factors: (i) the volume V (e.g., in terms of gallons) of water used during a cycle; (ii) a clothes density adjustment factor D (such as 0.94); (iii) the temperature T (e.g., in degrees Fahrenheit) of the water; and, (iv) a constant K which relates power usage to volume and temperature. The quantity 0.0024 kWh/(Gal.)(.degree. F.), for example, may be used for the constant K. Thus, the energy factor EF is determined according to the following equation: EQU EF=(V)(D)(T)(K). (1)
It should be noted that a cycle of operation or cycle as used herein means the operation of the appliance from the time that the appliance turns on to begin the processing of a load until the appliance turns off following the complete processing of that load. A cycle may be divided into a number of subcycles. For example, a cycle of a dish washer may include one or more wash subcycles, one or more rinse subcycles, a drying subcycle, and the like. It should also be noted that, if the metric system is used for the units of V and T, the magnitude of K should be changed accordingly.
New standards are expected to be implemented which may require even higher efficiency standards. Accordingly, the acceptable maximum energy consumption level is expected to decrease. In terms of a washing machine, the acceptable energy consumption level directly affects the amount of hot water usage per cycle. Additionally, credits may be used to adjust the calculated energy factor for an appliance if the appliance implements certain energy saving operations. For example, if a clothes washer provides higher spin speeds suitable for obtaining greater water extraction, the higher spin speed thereby reduces the energy requirements of a dryer. Accordingly, an energy credit would be given to the clothes washer if it implements higher spin speeds.
The present invention is directed to an appliance controller that is flexible enough to comply with changing requirements regulating maximum energy usage.